The present invention relates to a screw conveyor apparatus for a steep slope and large lifting height which conveys plastic materials such as sediments or ores, or grains or scattered materials along a steep slope up to a high position.
As a well-known technique, the inventor of this invention has proposed, for example, in Japanese Patent Publication No. 60-43518 specification, a screw conveyor that conveys grains, scattered materials, or sediments along a steep slope (within the range between 30 and 90xc2x0) during an operation of unloading containers from a hold or exhausting sediments from a tunnel shaft. This screw conveyor comprises a cylindrical casing in which a ribbon screw is rotated and supported at its top and has a hollow portion with a central shaft located therein. The term xe2x80x9cribbon screwxe2x80x9d, as used herein, refers to a helical twisted strip that does not have a central shaft or support spokes.
However, with the above described configuration, if the slope is very steep (30 to 90xc2x0 from the horizontal line) and the lifting height is about 20 or more times as large as the outer diameter of the screw, the weight of conveyed materials becomes so large that the ribbon screw may be expanded in the axial direction or the conveyed materials are caught in the gap between the ribbon screw and the central shaft or between the ribbon screw and the cylindrical casing. As a result, the ribbon screw may be twisted and bent and further expanded and contracted in the axial direction, thereby reducing the conveying capability of the conveyor to prevent the conveyed materials from being conveyed smoothly.
To prevent this, it is contemplated that the thickness of the ribbon screw may be increased. However, increasing the thickness has the disadvantage of increasing the weight of the ribbon screw, resulting in the need for a high drive force and an increase in manufacture costs.
Further, to increase the lifting height, the screw conveyor may be composed of a plurality of stages connected together via screw overlapping portions so that the axis of the screw is offset between the stages. However, in this case, transfer resistance may occur in the screw overlapping portions to stall conveyed materials.
It is thus an object of the present invention to provide a screw conveyor apparatus for a steep slope and large lifting height which can efficiently convey materials while preventing the ribbon screw from being bent or expanded or contracted even with a steep slope or a large lifting height, without any need to increase the thickness of the ribbon screw.
The present invention set forth in claim 1 is a screw conveyor apparatus for a steep slope and large lifting height, having a ribbon screw disposed in a cylindrical casing so as to be rotatable around an axis of the ribbon screw, characterized by comprising: rotation rings fixedly fitted over the ribbon screw at predetermined positions in an axial direction of the ribbon screw; and outer peripheral supporting sections provided in the casing and supporting the rotation rings so that the rotation rings to be rotatable.
With the above described configuration, the ribbon screw is supported by the casing via the outer peripheral supporting sections. Accordingly, even if conveyed materials are caught in a gap between the ribbon screw and the casing or if a load heavier than the conveyed materials is imposed on the ribbon screw, the ribbon screw is prevented from being twisted, bent, deformed, or expanded or contracted in the axial direction, thereby restricting a decrease in conveyance efficiency.
The present invention set forth in claim 2 is a screw conveyor apparatus for a steep slope and large lifting height, having a ribbon screw disposed in a cylindrical casing so as to be rotatable around an axis of the ribbon screw, characterized by comprising: rotation rings fixedly fitted over the ribbon screw at predetermined positions in an axial direction; outer peripheral supporting sections provided in the casing to support the rotation rings to be rotatable; a main screw rotating device provided at a predetermined position of the casing to rotationally drive the ribbon screw; and an auxiliary screw rotating device provided for at least one of the outer peripheral supporting sections to rotationally drive the ribbon screw via the rotation rings.
With the above described configuration, the main screw rotating device can rotationally drive the ribbon screw, and the auxiliary screw rotating device can apply, in an intermediate portion of the casing, a rotational drive force to the ribbon screw via the outer peripheral supporting sections. Consequently, the support of the rotation of the ribbon screw can be separated from the transmission of drive force, thereby preventing the ribbon screw from being twisted, bent, deformed, or expanded or contracted, while allowing the screw to be rotationally driven smoothly even with a large lifting height.
The present invention set forth in claim 3 is the screw conveyor apparatus according to claim 1 or 2, characterized in that the ribbon screw is formed by connecting a plurality of screw pieces together in the axial direction, the screw pieces each have a recess and a projection formed at respective connected ends thereof, the recess and projection being capable of engaging with each other in a screw surface so that the screw pieces can be freely coupled together and separated from each other, and coupling members are provided for coupling the screw pieces together using the recesses and projections.
With the above described configuration, the plurality of screw pieces are connected together to form a longer ribbon screw, thereby easily providing a screw conveyor with a large lifting height. Further, the connected ends of the screw pieces are connected together using the coupling members by engaging the recesses and projections with each other, thus allowing the screw pieces to be easily and firmly connected together.
The present invention set forth in claim 4 is the screw conveyor apparatus according to claim 1 or 2, characterized in that the ribbon screw is formed by connecting a plurality of screw pieces together in the axial direction, the screw pieces having connected ends each cut at a traverse surface perpendicular to the axis, with connection rings fixedly fitted over the respective cut portions, the connection rings are connected together to connect the screw pieces together, and integrated connection rings obtained by coupling the connection rings together form outer peripheral supporting sections supported by the casing to be rotatable around the axis so as to support the ribbon screw on the casing.
With the above described configuration, the integraged connection rings connecting the screw pieces together are rotatably supported by the casing to reinforce the connected portions of the screw pieces of which strength is prone to decrease, thereby effectively preventing the screw from being twisted, bent, or expanded or contracted in the axial direction. Further, a longer ribbon screw can be easily formed, and it is possible to convey materials up to a high position.
The present invention set forth in claim 5 is the screw conveyor apparatus according to claim 1 or 2, characterized in that the ribbon screw is formed by connecting a plurality of screw pieces together in the axial direction via coupling pieces, the coupling pieces are fixed to the rotation rings via coupling means, a recess and a projection are formed in ends of the coupling pieces and in connected ends of the screw pieces, the recess and projection being capable of engaging with each other in a screw surface, and the screw pieces and the coupling pieces are continuously connected together along the screw surface at a same inclination.
With the above described configuration, the plurality of screw pieces are connected together via the coupling pieces to form a ribbon screw, thereby easily providing a long ribbon screw conveyer with a large lifting height. Further, the recesses and projections formed at the ends of the screw pieces and at the connected ends of the coupling pieces are engaged with each other and connected together with the coupling members, thereby enabling the screw pieces to be easily and firmly connected together via the coupling pieces. Furthermore, the coupling pieces are each connected between an upper screw piece and a lower screw piece at a same inclination, thus enabling materials to be smoothly conveyed, while precluding the coupling pieces from degrading the conveying capability. Moreover, for maintenance, the screw pieces or the rotation rings can be easily installed and removed by separating the coupling pieces from the screw pieces, so that worn-out parts can be easily replaced with new ones, repaired, or disassembled and adjusted.
The present invention set forth in claim 6 is the screw conveyor apparatus according to claim 1 or 2, characterized in that the ribbon screw is formed by connecting a plurality of screw pieces together in the axial direction via coupling pieces, the coupling pieces are fixed to the rotation rings via coupling means, a recess and a projection are formed in ends of the coupling pieces and in connected ends of the screw pieces, the recess and projection being capable of engaging with each other in a screw surface, the screw pieces and the coupling pieces are continuously connected together along the screw surface at a same inclination, and the coupling means comprises a notched portion formed at a predetermined position of the coupling piece which corresponds to an inner surface of the rotation ring, a mounting piece that can be fitted in and removed from the notched portion, a fixing member that fits the mounting piece in the notched portion to fix it to the coupling piece, and a welded portion in which the mounting piece is joined to the rotation ring.
With the above described configuration, the mounting piece is fitted in the notched portion in the coupling piece to connect the rotation ring to the coupling piece, so that the coupling piece and the rotation ring can be easily disassembled by removing the mounting piece welded to the rotation ring, from the notched portion in the coupling piece. Thus, the coupling pieces, which are prone to be worn out or damaged, can be easily separated from the rotation rings, improving maintainability.
The present invention set forth in claim 7 is the screw conveyor apparatus according to claim 1 or 2, characterized in that an axial width of the rotation ring which protrudes into the casing is in a range of 0.05 to 0.6 times an outer diameter of the screw.
With the above described configuration, the width of the rotation ring which rotates with conveyed materials is set to fall within the range of 0.05 to 0.6 time the outer diameter of the screw. Consequently, the pressure loss of the screw conveyor associated with the rotation rings can be reduced to minimize lowering in conveyance efficiency, and to ensure sufficient mechanical strength which contributes to supporting loads and transmitting power.
The present invention set forth in claim 8 is the screw conveyor apparatus according to claim 1, characterized by further comprising: casing pieces formed by dividing the casing into a plurality of pieces in the axial direction in correspondence to the outer peripheral supporting sections; support rings respectively attached to connected ends of the casing pieces; rotation rings each rotatably supported between the support rings via a seal portion; and a bearing housing each provided between both support rings to cover the rotation ring.
With the above described configuration, the support rings connected to the ends of the casing piece rotatably support the rotation rings, thereby allowing the rotation rings and the support rings to be easily assembled and disassembled, while allowing the rotation rings to be stably supported.
The present invention set forth in claim 9 is the screw conveyor apparatus according to claim 2, characterized by further comprising: casing pieces formed by dividing the casing into a plurality of pieces in the axial direction in correspondence to the outer peripheral supporting sections; support rings attached to the respective connected ends of the casing pieces; rotation rings each rotatably supported between the support rings via a seal portion; a bearing housing provided between both support rings to cover the rotation ring; and an auxiliary screw rotating device provided in the bearing housing, the device comprising a drive pinion that meshes with a passive gear provided on the rotation ring and a rotational drive device that rotationally drives the drive pinion.
With the above described configuration, the support rings connected to the ends of the casing piece rotatably support the rotation rings, thereby allowing the rotation rings and the support rings to be easily assembled and disassembled, while allowing the rotation rings to be stably supported. Further, the outer peripheral supporting sections can be used to easily arrange the auxiliary screw rotating device in an intermediate portion of the casing.
The present invention set forth in claim 10 is the screw conveyor apparatus according to claim 1 or 2, characterized in that a loading screw conveyor is connected to a lower end of the casing, and loading means is provided at a tip portion of the loading screw conveyor to collect and supply conveyed materials to the loading conveyor.
With the above described configuration, the loading means supplies conveyed materials to the loading screw conveyor, which further forcibly supplies them to the interior of the cylindrical casing, thus enabling the conveyed materials to be conveyed along a steep slope up to an upper position even when the materials are grains. Further, the loading means allows conveyed materials to be easily and smoothly unloaded from, for example, a hold in a cargo vessel which has corners.
The present invention set forth in claim 11 is the screw conveyor apparatus according to claim 1 or 2, characterized in that a loading screw conveyor is connected to a lower end of the casing, loading means is provided at a tip portion of the loading screw conveyor to collect and supply conveyed materials to the loading conveyor, and the loading means is composed of a reclaimer device having a bucket wheel driven to rotate around a predetermined axis.
With the above described configuration, the reclaimer device can feed a large amount of conveyed materials into the casing via the loading screw conveyor to fill the casing with the conveyed materials, thereby efficiently achieving a lifting operation.